Prerequisites

This tutorial assumes you have already configured the CUPS printer server. There is plenty of existing information to get this working.

Download Brother HL-2250ND drivers

Create a temp directory such as ~/brother

Download the RPM packages of the CUPS wrapper (HERE) and the LPR driver (HERE) and place them into your newly created temp dir

Extracting the RPM files

You'll need to grab a script to extract the files from the RPM packages, so log in as root and execute:

# pacman -S rpmextract

Then extract both RPM files:

$ rpmextract.sh *.rpm

You should now have two sub-directories: usr and var

Editing files to make them work with Arch

Arch Linux uses its own filesystem hierarchy, so you must edit some files to match it. We'll assume you created the temp directory brother in your home directory as mentioned earlier.
Use your favorite text editor (i.e. kate, gedit, or vi) and open

Installing the driver and printer

Upon completion the script will attempt to restart the CUPS daemon if it was running.
Now browse to the CUPS server : http://localhost:631/

Under the Administration category, choose Manage printers. You should now see your HL2250DN printer automatically installed and configured, for USB connection.

Configuring the connection

Follow step 5a for USB connection, and step 5b for a network connection, on this page.

Print a test page and configure the printer settings to your liking.

Auto start

You will want to edit the /etc/rc.conf file to start cups on every reboot.
Add cupsd to the daemon list.

Regional Settings

Make sure to set your printer preferences to match your region. For example, if you live in North America (Canada, US, Mexico) your paper size should be changed from the Default "A4" to "Letter". Sometimes this will be done automatically by your Desktop Environment (e.g. KDE) but it's worthwhile to check it yourself or the text on your pages won't align properly.

Alternative Options

I failed to get the above to work for various reasons, but am having moderate success with the Generic PCL Laser Printer driver over IPP.